Thread: Changing cutter angle

Originally Posted by timbertalk

Well I finally did what I have been wanting to do for some time - changed chain cutter angle. I decided to do it in 2 stages, the first of which I did today, from 30 to 20 degrees. This was BETWEEN slabs, same log, so I could really tell what difference it made. Well it was huge(ish), and as predicted by theory. The two biggest effects were (1) much smoother milling, and (2) chain kept its edge much longer, maybe twice as long. While initial cutting speed was similar, freshly sharpened, the 30 degree lost its edge and cutting speed slowed much quicker. It was much more prone to 'bogging down' too. Chip size was proportional to cutting speed in both, so after several slabs, chip size was bigger with 20 degree cutters. Next sharpen will be to 10 degrees. Although the importance of cutting angle has been known for 30 years, thought you might be interested.....

Been there and done that But seriously it is very instructive to do it for yourself. As you keep decreasing you will reach a speed, cutter longevity, smoothness/vibration compromise dependent on species and dryness. I have been all the way down to 2º topplate angles -exceptionally smooth cut with longer lasting cutting but slower cutting speeds

we run 7 chains with 15 degrees, Each chain is swapped out after about 32SqrFt (8x4 slab) of hard wood then we just skim the face of each tooth and she's right to go for the next cut, when removing the chain are they hot to touch..? we find ours get hot if they get blunt, one thing I have noticed is that when a chain is getting blunt the links start to gum up with resin or caked on sawdust, can really notice it on those big long slabs

Salty

Originally Posted by salty72

we run 7 chains with 15 degrees, Each chain is swapped out after about 32SqrFt (8x4 slab) of hard wood then we just skim the face of each tooth and she's right to go for the next cut, when removing the chain are they hot to touch..? we find ours get hot if they get blunt, one thing I have noticed is that when a chain is getting blunt the links start to gum up with resin or caked on sawdust, can really notice it on those big long slabs

Yep that is my observation as well. Blunt hot chain heats the water in the wood and that dissolves some of the resins which stick to the chain. It's a bit tree dependent, Tuart for example gums up no matter what you do.

Yes Bob, there is nothing like seeing the results with your own eyes. I took it further today, to 10 degrees, in the rain - couldn't resist a testrun. Another leap in smooth running, and fast. Only did one cut before too dark, but the slab was almost mirror smooth, and clean as a whistle. How long the edge lasts is yet to be seen. I can't imagine further improvement is possible, but we'll see. And Salty, I hope as you say that the other bonus is that a quick touchup with file or 12volt grinder will give an appreciable amount of extra slabbing before a full re-sharpen. The reason I have done a lot of slabbing with 30 degree topplates till now is that I got 50 feet of cheep crosscut chain, but in future will grind this to shape quicksmart.

Originally Posted by timbertalk

.................. I have done a lot of slabbing with 30 degree top plates till now is that I got 50 feet of cheep crosscut chain, but in future will grind this to shape quicksmart.

What sort of chain was the cross cut..? Was it 27RA.?? (single skip - left / Right / miss / Left / Right) - If you run a 27RX 3 or 5 skip you will get better results.

you might want to consider grinding off cutters to give you a cheep alternative, but ensure you grind them to give a
LEFT / RIGHT ...Miss.a few ..RIGHT / LEFT ,

This will ensure that the chain will not "Snake" from one cuter to the next as the teeth cut fresh timber - also if you have less teeth you will require less H.P. and surprisingly you actually cut faster

here is a photo of a Tassy Blue gum (part of the Tassy Oak family) -Hopefully you can see on the close up the quality of a 27RX 5 skip with 15 degree grind

That is a great finish, I think you are onto something! Seems you have settled on 15 degrees for a reason, have you tried lower angles?. My crosscut chain was from GB, skiptooth, says "A3" on the chain, but is just left-right-left-right, spaced by two links each. Is 27RX a Carlton chain?

i have always found skip chain i made myself cut better than the baught stuff.

on small slabs up to 1m i like 2 on 3 off for larger you can go 2 on 5 off. but you have to remove an odd number of cutters.

Yes, that is consistant with what salty was saying. What cutter angles do you use Carl?

i run my lucas slabber chains at 15-20*.

because i have a 25hp motor running the mill. i have 2 on 3 off chian and the depthgauges cut back 3 times what they normaly are.

we cut a mango log yesterday and a slab 3m long x 1.3m wide taking 2 mins there was no sawdust just little lumps of wood. i meant to take a pic but forgot. nice smoth finish aswell.

on the chainsaw slabber i rant the chain at 20* single skip.

Unless I'm dreadfully mistaken (entirely possible, of course), ordinary chain saw use is for cross-cutting, hence the "standard" 30-degree angle. Milling is more akin to rip cutting, and benefits from a flatter angle.

Otherwise, what they all said.

Cheers,
Joe

Originally Posted by timbertalk

That is a great finish, I think you are onto something!

Seems you have settled on 15 degrees for a reason, have you tried lower angles?.

Is 27RX a Carlton chain?

Timbertalk, the specifications given are just the standard specs advised by Lucas and also Oregon.

15 degrees gives a slightly quicker cut than 10 degrees. Having said this, I use 10 degrees and a few days ago 'cleaned' up some Cadaghi slabs - O.6mm cut on the electric plane cut out all evidence of sawmarks from the chain, other than in spots where the slab had dried a bit badly, like around knots and the heart.

27RX is oregon chain, but also is only 5 skip not 3skip and/or 5skip as previously mentioned. Oregon do not manufacture a 3 skip 27R chain, the 27R 3 skip chain is something Lucas make themselves.

Also the pattern that Salty is advising (left, right.....right, left) is just the standard pattern that 27RX comes from factory.

Mark (aka Salty72) why are you asking if Timbertalk's 50' of crosscut chain is 27RA? With all your experience you should know that 'R' designation in 27RA means a "ripping chain featuring a special grind for use in ripping cuts only"

Almost off my soapbox, but there is something to be said for crediting the source of information, always upsetting when your brother asks for your hard earned advice and knowledge and then goes off sprouting it like he invented it...

Off my soapbox now.

Timbertalk you're are getting good advice despite where it originates.

Thanks Allan, that's clarified a few things. As you illustrated, extra time and care taken in milling is regained twofold in the dressing.

Just wondering about the sequence, I would've thought that u would want a left right left pattern as the following left or the following right wouldnt be doing much cutting in a left left right right pattern.

There still has to be a point in the sequence where it swaps from a left to a right and then right to left so the reasoning for having a left left right right eluds me Please explain.

Granted that depending on number of cutters in a chain u could have a left or right following a left or right but only two as I found out when I made a 3 skip

Peter.

You are right Peter, I've pondered this often too. when you have a pair of cutters they are opposite anyway, so this whole 'snaking' concept eludes me too, as you say they have to alternate somewhere in the chain.

I haven't a clue what the original rational was behind right, left _ - _ - _ left, right - _ - _ - right, left other than by skipping 5 or 3 cutters (aside from the obvious cutting gains) it's an odd number and so it's just how the chain ends up and I suppose after a bit of experience, Lucas and others before us, found the sequence made no detriment as compared to an even skip, say a 4 skip, which would produce right, left _ - _ - right, left _ - _ - right, left.

I know Oregon's 27RA is a right, left, right, left, right, left configuration and I've used it until I was tired of sharpening it (too many cutters on 163 drive links, in the 27RX configuration there are only 13 pairs of cutters) and I saw no adverse effects to using a 'normal' configuration chain, it cut pretty quick, gave a good finish, motor handled driving a heap more cutters, but very limited for how wide you can slab; so that and the sharpening time was why I don't use it anymore.

As a bit of a side note, I was slabbing yesterday, just a quick job. using 27RX with 10 deg top-plate angle and 10 deg (off perpendicular to the chain) file-guide angle, the Carlton file-o-plate to file raker clearance, cut 5 silky slabs from the top half of a 3.0m log 2 3" and 3 2" widest being 800mm 1 sharpen (by hand) prior to cutting, no resharpening; last slab was 4.2min to cut.

Then we swaped out the remaining log for this;



I resharpened the same chain keeping everything as above, except changing to 15 deg top-plate angle and cut out about 7 (I think) 80mm biscuits all around the 850m diameter.

Then we chucked in an interesting shaped bluegum log (sorry no pic) suffice it to say it had a tight fork at the top for about 2' and also about 18" in from the bottom it branched out both sides, with each branch being around 10"dia, the bottom of the log was around 500mm diameter and was 2.4m long. Again same chain, no resharpen, cut out 4 60mm slabs and left the bottom third for firewood. The finish on the bluegum was much more pronounced than the earlier finish on the SO, the two fella's I was working for(Peter and Dave) where very surprised at the finish and Peter is into his 13th year of owning a Lucas Mill - doesn't have a slabber though I should have got a pic of the two finishes - it would have been very good for people to see a big difference between the 15 deg finish and 10 deg finish. Also with having the 15deg on the bluegum it kept the speed up even though I didn't touch up the chain after doing the biscuits.

So two sharpens for 4 x 2.4m bluegum slabs, about 7 x 850mm diameter SO biscuits and 5 x 3.0m SO slabs up to 800mm wide